Pure speculation on my part......people make decisions
everyday based on what they see in Microsoft products.
Now, in an ever increasing manner people are making
decisions on what they see in future Microsoft products
(Whidbey, etc.). It would be a bad thing for Microsoft
if someone were to see X# and make decisions based on
its current state as well as the idea that it may be a
product someday when in fact it may not. This scenario
is much like Microsoft releasing the product
specification for something they've just begun to build.
There are lots of things that get cut from products
throughout the life cycle for various reasons and it is
usually better that folks find out the features that
will ship with the product rather than the sky high
expectations of the team (or in this case a research
group).
I'm sure competition is something that would be a factor
as well.